Method of and apparatus for applying finely-divided material to grinding and smoothing mechanism.



H. K. HITCHCOCK. METHOD OF AND APPARATUS FOR APPLYING FINtLY DIVIDED MAW-MAL ro GRINDING AND.

SMOOIHING MECHANISM. APPLICATION FILED AUG/J 191s Q a $1 2 Q Q 1 Q; Q m '0 Y L f 3&3

to l L I! E I. g Q1 WITNESSES INVINTQ' H. K. HITCHCOCK. METHOD OF AND APPARATUS FOR APPLYING FINELY DIVIDED MATERIAL T0 eamomq AND SMOOIHING MECHANISM. APPLlCATiDN FILED AUG.9.19!5

1,3 1 1 ,5171 A Patented July 29, 1919.

H 3 SHEETS-Shtnf 2.

' H. K. HITCHCOGK. METHOD OF AND APPARATUS FOR APPLYING HNELY DWIDED MATERIAL T0 GRINDING AND SMOOIHING MECHANISM. APPHCATI'DN man AUG.9,1BX5

Patented July 29, 1919.

UNITED STATES PATENT OFFICE.

HALBER'I K. HITCHCOCK, OF PITTSBURGH, PENNSYLVANIA.

METHOD OF AND APPARATUS FOR APPLYING FINELY-DIVIDED MATERIAL '10 GRINDING AND SMOOTHING MECHANISM.

Specification of Letters Patent.

Patent-ed July 29, 1919.

Application filed August 9, 1915. Serial No. 44,622.

Be it known that l, llannlurr K. I'IITGH- cent. a resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Methods of and Apparatus for Applying l inely-Dividml Material to Grinding and Smoothing lll echanism. of which the following is a specification.

This invention relates to method and. apparatus for grading abrasives and supplying the same to grinding machines, and particularly for grading sand or other abrading material and supplying the same to apparatus for grinding or finishing plate glass.

One object of the invention is to improve the grinding and finishing operations by more accurate classification or grading of the abrasive material, to thereby reduce the total time required for grinding and finishing a single side of glass and secure more eliicient operation and an improved product. A further object of the invention is to provide a method and apparatus which pro duccs in a single vessel. a cleaner and more. accurate separation or classification of the difi'erent. grades of abrading material and avoids contamination of one grade by any other grade. and also produces a. denser mix ture of the abrading material with the liquid in which it is suspended, so that the grinding and finishing operations can be carried out more economically, with less liquid, less handling of the material, in a shorter time and with as simple an apparatus as possible.

A further object of the invention is to PM vide a method and apparatus enabling the grading operation to be carried on under uniform conditions with the production of sharply diti'ercntiated grades of material which are maintained at various levels in the grading vessel, so that the operator can rely upon the accuracy of each grade of abrading material at the various levels in the grading vessel. A further object of the invention is to provide a method and apparatus in which the abrading material is supplied to the grading vessel in suspension in a liquid at a level intermediate its bottom and the upper level of liquid therein, so as to secure a sharp classification or grading of the material and prevent contamination of one grade by another, and in which the grading operation is produced by the upward .flow or travel of a stream of clear liquid introduced to said vessel, so that the conditions for grading in said vessel are maintained substantially uni form and are independent of the exact rate of supply of the abrading material to said vessel and of the speed of operation of the supply pump. A further object of the invention is to secure a dense mixture, especially of the liner grades, by eliminating from the various levels in the grading vessel the superfluous liquid, so as to maintain a sufiicient supply of the finer grades in suspension without the necessity of collecting the finer grades of abrading material in a separate grading'vessel and settling the same. thereby securing more'rapid and ellicient Operation of the apparatus during finishing. A further object of the invention is to provide an improved method and apparatus wherein the rough grinding is carried on 'in a continuous cycle of circulation with the material constantly in suspension in a liquid, the finer grades being collected in the same grading vessel and condensed by elimination of the surplus liquid and subsequently con ducted tothe grinding apparatus for the finishing operation. Further objects of the invention are in part obvious and in part will appear more in detail hereinafter.

In the drawings, Figure 1 represents in diagrammatic sectional elevation one form of apparatus embodying the invention; Fig. 2 is a detail sectional elevation, on a larger scale, through the gradin vessel; Fig. 3 is a plan view thereof; an Fig. 4 is a diaurannnatic sectional elevation of another orm of apparatus embodying the invention.

Referring to the drawings, 1 indicates a grinding table equipped with a pair of runhers 2 of the usual form. Said table is surrounded by a gitter 3 communicating with a conduit 4 which conveys the liquid and used abrading material over a screen 5 to a sump or pit 6, having the usual overflow' 6 for elimination of the excess liquid, the slimes and the material too fine for further use. From the sump the mixture is withdrawn through a. pipe 7 by the centrifugal pump 8 and delivered to the grading vessel 9. The grading vessel is arranged to grade the new material, regrade the used material and separate the various grades and main tain them at different levels. therein, from which levels the several grades may withdrawn independently and in any dosired sequence through several withdrawal pipes 10, 11 and 12 to a trough 13 for conducting the abrading material by gravity to the grinding table 1. One of said pipes, such as the pipe 11, may be a flexible tube long enough to reach to the bottom or top of the grading vessel and having its free end weighted and connected to suitable devices on the outside of the grading vessel for moving it to any level therein, so that mix ture can be withdrawn through said pipe from any level in the rading vessel. One suitable arrangement or this purpose is shown in m prior application, Serial N 0. 806,594, filed December 13, 1913, and therefore re uires no further description. The fresh 0. rading material or sand can be added to the system at any point, but prefer abl is supplied directl to the sump or pit 6 mm a hopper 14 .ed by a clam shell bucket or other suitable device, preferably being added in measured batches, one before (or at least during the first part of) each grinding operation. The grading vessel is provided with the usual overflow pipe 16, for carrying away the scum, superfluous liquid, and abrading material too fine for further use, said pipe leading to the gutter 3 so that the liquid carried thereby can be utilized for washing out the gutter and ditches around the table. So far as described to this point the apparatus may be of the same general kind shown, for exam he, in Fig. 1 ofmy prior Patent No. 1,089, 05, dated March 10, 1914:.

According to the present invention the grading operation in the vessel 9 is carried out in a manner to utilize the general principles set forth in my prior Patent 1,100,302, dated June 16, 1914, and grades or classifies the material while in suspension in a liquid in the rading vessel by the action of a current 0 liquid having an upward flow or travel relative to a downward movement of the material, which separates and classi fies the several grades in different strata in said vessel, the finer grades near the top and the coarser grades near the bottom. The material to be graded has heretofore been introduced into the grading vessel either at its bottom, as in my Patent 1,100,302, or at the upper level of liquid in said vessel. when introduced at the bottom the finer grades are carried upwardly by the upward flow o travel of the liquid relative to the material and pass in turn the outlets through which the several coarser grades are withdrawn. Some of the fine material therefore unavoidably passes out through the various openings when the apparatus is run continuously. On the other hand, when the abrading material is introduced at the upper level of liquid in the gradin vessel the coarse material falls past the out ets for the several finer grades. so that said grades are crmtaminated by some of the coarser material, or, a considerable time must be allowed for the course material to reach equilibrium at its proper levels before the line material can be withdrawn to the grinding apparatus during finishing.

.In the present invention the material to be graded is llllll'UtlllLQtl into the grading vessel at a level intermediate its bottom and the upper level of liquid. therein, thereby enabling the coarser material to travel dowiu vvardly against the rising current of liquid and the finer grades to travel upwardly with said current, so that all rades of material find their proper levels without contaminating one grade with material from another. The mixture of liquid and finely divided material to be graded is preferably intro duced into the grading vessel in an upwardly traveling stream, for example, through a nozzle 17 supplied by the pump 8 and extending into said vessel, preferably upwardly through its bottom, and terminating at a level intern'iediate its bottom and the upper level of liquid therein. The bottom of the gra ling vessel is provided with an inlet 18 for a clear liquid supply to produce or augment the upward flow or travel of the liquid relative to the material and produce the grading action. This clear liquid supply is preferably under a sufficiently high pressure so that it'produccs the effective upward flow or travel oi the liquid for the grading operation. and the exact. speed of operation of the pump is is more or less immaterial, as slight variations in the speed of said pump do not appreciably affect the velocity of upward flow of the liquid which produces the grading action. Moreover, a pump operated by a motor on a constant potential circuit runs practically at constant speed. The density of the grinding mixture is regulated by the auxiliary clear water supply, which is only a small ercentage of the total volume of liquid. lonsequently the pump can be run at practically constant speed without any elaborate apparatus to secure exact regulation.

The outlet for the coarsest grade or grades through. the pipe 10 may be located at any suitable level, but is preferably located at a level between the inlet 18 for the clear liquid supply and the mouth of the nozzle 17 where the material to be graded is intro- 'duced to the grading vessel, so that said 1 outlet lies in a zone or stratum not traversed by any of the finer grades. Consequently, an extra clean coarse grade or rades can be withdrawn from this region 01% the grading vessel. The clear liquid supply travels upwardly through the grading vessel with the mixture of liquid and material to be graded, but the velocity of upward travel of the liquid relatively to the downward flow of the material at and near the inlet for the mixture is not suflioient to carry any of the coarser particles upwardly, but is merely suflicient to lift the finer grades to their proper levels in the grading vessel.

In operation of this system the pump 5 supplies ahrading material in suspension in the liquid from the sump or pit to the grading vessel and the grading operation is carried' on continuously so that a sufficient supply of graded abrading material is always collected at the proper levels in the grading vessel. During the rough grinding operation the coarse material in suspension in the liquid is withdrawn through pipe 10 and conducted by trough 13 to the grinding table and is thrown into the gutter ii and flows through ditch l to the sump (i, where the excess water and slimes are eliminated through the over flow 6, and from which the mixture is returned to the grading vessel to he regraded therein. The grading and regrading with the material constantly in suspension in a liquid, and the cycle of circulation from the grading vessel to z il from the rinding apparatus go on contiiu ously unti the rough rinding or facing up oration is finished. uring this operation the finer grades in the grading vessel are collected for use during the finishing opera tion, but without contamination hy the coarser grades, which are supplied to the grading vessel at a level below the finer grades and therefore do not contaminate the same. \Vhen the rough grinding or farm ing is concluded the supply of coarse nutterial through the pipe 10 is shut oil" and the finishing is ell'eeted by witlulrawing the several finer grades through the pipes 11 and 12 in succession or in any desired sequence and conducting them to the lahlc. During such finishing these finer grades may be circulated to the grinding apparatus and back to the grader, or not. as desired. At the conclusion of the rough grinding or facing operation the supply of material to the gradin vessel from the sump may be discontinue after a suliielent time has elapsed to collect the ropor quantity of finer grades in the gra ing vessel, but preferably is continued without interruition during both rough grinding and finishing so as to maintain in the grading vessel at all times as much of the ahrading materinl as possible.

The finishing operation is more advaxr tngcously effected when the mixture of ma terial,,has a certain density, which density is greater than that ordinarily found in any single grader grading apparatus heretofore used. Suitable means is therefore provided for eliminating the surplus liquid from the various levels in the rading vessel without withdrawing any of t e useful fine material therefrom, so as to secure the desired density and distribution. of the mixture. In the apparatus shown the grading vcsscl 9 has a coniral lower portion :3!) which produces a decreasing upward velocity of flow or travel of the liquid relative to the material at the vari us lcvcls therein to collect or classify the coarse grades, and a evlindrical upper portion 21 which serves as a supplemental gradcr for the liner grades super posed upon the lower or conical portion of the vessel, and which traps various finer grades at different levels therein. \Vithiu the oylil'zdrical upper portion :21 of the grad ing vessel located an annular gutter or trough in receive an overflow of the liquid in the guiding vessTfl over the inner wall of the gutter, The bottom of the gutter is incli ed downwardly in opposite di- I'rctions circumferenl'ially of tl1e,grading vessel from one side to the other. and at ils lowest part. said gutter comn'iunicatcs through an opening in its side wall and through the side wall of the tank with the overflow pipe 16. Within the cylindrical portion of the grading vessel and at different levels liwrrin are located a series of small hollow dehydrating cones ll communirating an upwardly extending pipes 25 discharging into the gutter 22, said pipes being provided with suitable regulating valves 26.

hen lilo valves Ql' are fully closed no liquid or ahradiug material can flow upwardly into or through the cones 2i. hut if said valves are opened the liquid lion's out through the cones E24 and pipes 33 into the gutter 111:. the velocity of flow increasing with the sire of the opening through said elves. \Vheu liquid is flowing upwardly through the cones :21 and pipes '25 the velority of flow increases from the bottom of the cones upwardly and reaches a maximum at the pipe 5 Eaeh valve '26 is adjusted so that the vrle'icity of flow in its cone at a level between its top and bottom, say at the line B, Fig. equal to the velocity of flow of the mixture in the grading vessel at the level A of the helium of the cone. The W- loclly of flow of the liquid between lcvcls A and ll is therefore something less than at said levels and is insullicieut to lift any ahradiug material lying in equilibrium at the level A into the cone 24. Consequently each (one abstracts or removes from the grading vessel at its particular level some of the liquid of the mixture but without removing any ahradiug material normally helonging in that zone. l

The discharge of liquid at each of the cones 24- progressively reduces the upward velocity in the cylindrical portion '31 of the grading vessel by a series of steps, so that the finer rades are separted into groups distributed at various levels in the grading vessel. At each level a certain grade or size of material between definite limits gradually arculnulates each grraulchumming morn and morn (ii-mo as llll' ill-hydrating opvratiou pror'rr-ds. Tho Qjitiiirs iacoino gradually tinmand iinor upwardly at the tlltllilmlt levels in tho russul as the iutrrstioial volooit of the liquid di-i-rrasos, The several mom-s iuiWOOn tho bottoms of tho inrortvd (our-s LZ-l tlwrvture form a series of traps, uurh arrimuilating its own particular grado of line material. and the cones oondrnso it, h v distracting tho suportluous liquid thorofrom. so that thvsv limu' grades are collected and storml during the several cycles of the rough grinding oporalion for later use dun imr finishing. 'lhv vharartor and position oiihvsi grades van in ri-g'ulati-d liv moans of the valves 2i Tho suprriiuous liquid withdrawn through the svi'rlal mnr's it. togut'hrr with tin over-- tlou' (HPl tho inm'r Wall 23 of the trough S22 lion's through tho pipo 16 to the gutter sur rounding tho grinding table and is utilizei'l for washing tho used ahrading matvrial hark into tho sumin living; linally olilninati-d from the yst'i-in through the overflow from the sump.

Full 4- illustruirs :lnoilirr form (if apparains vmliodving thiinvention and also servingg to rrgulatv the. supply of aln'ading matvrial to tho grading: vrssol by variations in tho drusiii of tlu= mixture in said vvssul, so as maintain said dvnsity substantially inii'nrni. prvirnlj variation in the grading! roudit ions in tluvrssrl and insuro the main tvnasmul' arruratv ratios of matrrial at tho dili'i-wnt h rl in the grading vrssol throughout tiw vntirroperation. as more tally (,lPt-it'l'llKli in my application for method and apparatus for grading finely divided unaturial. oi I'Yl'll datv hormvitln Srrial Nu 4462 In his form oi: the invention the matrrial to ho rradod is drliverod in susponsiun in a liquid to the grading \Pssel through a dvpeudin; pips or ronduit il whose bot tom opening is immersed in the liquid in said \rssvl at a suitahle level intcruaaliato ll bottom and tho uppcr level of liquid thorvin. for rxamplo, at a lovvl intermediate the lvvuls of the o wnings to the withdrawal pipvs it) and ll. The bottom of tho gradin; \irssrl is provided with the inlet 18 for a rlva' liquid supply to produce a definite upward lion in tho apvx of tho (one and to angnsrnt thr upward lion of liquid rolatlvr: to flu. n'mtrrial in tlw uppor part. This roals'o parIir-lvs in tho material to he grml d passing: in through the pipe fall downwardly against tho rising current from tho inlvt 1 thrvelocity' of said current bfilflg Mlilllit'lli to lift tluliner particles of ma ten'ial iivfoiv tho have a rhanoo to drop to the nntlut or nuth-ts for llu. (oat-5m gradi-s. tiu'i r-cplarut y a wry rluan voarsigrade oi maturial may ho wiilnlrawn. through that! pipev 10. The finer grades rise to the levels of the outlets for the finer grades, but no mat-so inatrrial is carried up with the fine, so that the several iinur grades withdrawn from tho pipes ll and 12 are clean and free from contamination hy the coarser grades.

Tho material to be graded is supplied to the pipe 30 from a supply box or vessel 35, located at the upper end of the pipe 30 and provided with a suitable hand-operated valvu ill; for controlling the flow of material from the iessel to the pipe 30. Material is supplied to the vessel by the centrifugal pump 8, the inlet to which immersed in the sump or pit (i, as before. Vessel 35 is also supplied with an overflow pipe 39 delivoring to the sump and connected to said vessel 35 at a lovel above the valve 36, so that when said valve is open a constant head or lwel of liquid is maintained in the suppl y vessel 35 at the level of the overflow pipi- 3!).

In operation of this system, during rough grinding, the valve 36 is open and the matorial delivered by the pump passes downwardly to the grading vessel through the pipv 30, the excess flowing hack to the sump through the overflow 39. T ho density Of the mixture in the grading vessel varies from time to time as the total quantity of material therein to be graded increases or diminishes, and the total quantity of matvrial in the grading vvssrl varies with the supply thereto and the amounts of the various grades withdrawn at the different, outlv'ts. While the downwardly moving stream of mixture introduced. into tho grading vessi-i is independent of or separated from the liody'iqf mixturo therein, the density of the body of mixture in the vessel nevertheless alive-ts the velocity of flow in the stream of mixture being supplied to said vessel. This is due to the fact that the column of mixture in the pipe or conduit 30, which has a ronstant head or pressure, is balanced against a similar column of liquid in the body of mixture in the grading vessel, but at a lower head or pressure. If the, weight or pressure produced by the body of mixture in the grader is less than that of the column of liquid in the pipe or conduit, 30 the prepondoratiug weight of the mixture. in the latter produres a more rapid downward flow thereof, while. on. the other hand, if the weight or pressure produced by the mixture in the grading vossel-is grvator than that in tho pipior u induiti 30 through l\l(l1 the mixture is introduced, then the proponderating effort of tho thody of liquid in the grading vessel toads to produro an upward flow of the mixture in the pipe 30. This effect partially or completely counteracts the normal downward How of the mixture in the delivery pipe 30 to roplace the mixture h0- lug Withdrawn from the grading vessel and causes more or less of the mixture ls ugr supplied to the grader to pass outv thron the overflow 3'9 and back to the sump, thus shunting the superfluous material around the grader. Consequently, the downward flow or travel of the mixture through the delivery pi pc or conduit 30 varies inversely with the density of the body of the mixture in the grading vessel, increasing as the density decreases and decreasing as the density increases, and tends to automatically govern or regulate the mixture being graded in the vessel so that it is maintained at a more nearly uniform or fixed density. This particular form of the invention is not claimed here, but forms the subject mattcrof my copending application Serial No. 4Al33, of even date herewith. 7

In both forms of the apparatus shown, during the. rough grinding operation the coarse material is circulated constantly in suspension in the liquid from the grading l'ernjvl to the grinding apparatus, thence to the sump and up again into the grading vessel, the circulation being continued unintcrrupo edly until the grinding operation finished. The supply of coarse material from the grader to the grinding apparatus is then shut. off. During the entire rough grinding operation the fine material is collected and dehydrated in the upper strata of the grading vessel ready for use during the finishing operation, which can begin immediately after the coin clusion ot' the rough grinding operation, without Waiting to collect a sufficient supply (it the liner grades. If desired, the sup ply of material to the grading vessel can be discontinued during the finishing operation, although it. is preferably continued without interruption at; all times so as to store the abrading material in the grading vessel rather than in the sump. -Thc accurate classification of the material by the method and apparatus described produce such an of ficient grinding action as to reduce the total quantity of abrading material and liquid required, and as a consequence it. is usually neressary to circulate the abrading mate rial from the sump to the grader continuously to insure the production of a sulficicntfl mount of fine material to complete. the thishing operation. If a large quantity oi abrading material is in the system, however. the supply of abrading mat rial to the gr nder during the finishing operation is not essential.

In the apparatus shown in Fig lthe sup ply of ahrading material to the grader is discontinued by closing the valve lli. but. without stopping the pump 8. so that the abrading material is delivered by the pump t the supply vessel 35 and returns directly t the vsump, thus by passing it aropnd the gnuliug vessel, in both forms of ,reiparw ins wllU'Wll the flow of clear liquid to tie hottom of the grading vessel for producing or augmenting the. upward flow or travel of liquid relative to the material is continued during the entire grinding and finishing operations. The dehydrating cones operate continuously during all stages of the grinding and finishing operations and serve to constantly collect and condense the liner grades in the upper portion of the grading vessel.

What I claim is 1. The method described, consisting in separating abradin material mixed with a liquid in a vessc into different grades, withdrawing said grades in any desired sequence and conducting the same to grinding mechanism, returning the same to the grading vessel and introducing the same into said vessel at a level intermediate its bottom and the upper level of liquid therein, simultaneously eliminating surplus liquid from various levels in said grading vessel, and introducing liquid into said vessel lucldw the level at. which the abradiug material is supplied thereto.

The method described, consisting in separating abrading material mixed with a liquid in a vessel into different grades, withdrawing said grades in any desired scquencc and conducting the same to grinding nuschanism, returning the same to the grad ing vessel and introducing the same into said vessel at a level intermediate the coarsest, and finest grades withdrawn therefrom, and simultaneously eliminating surplus liquid from various levels in said vessel while rctaining therein the ahrading material at said levels.

3. The method described, consisting in separating abrading material mixed with a liquid in a vessel into different grades, withdrawing said grades in any desired sequence and conducting thesame to grinding mecluu nism, returning the; same to the. grading vessel and introducing the same into said vesset at a level intermediate the coarsest and finest grades withdrawn therefrom, simultaneously eliminating surplus liquid from various levels in said vessel while retaining therein the abrading material at said levels, and simultaneously introducing liquid into said vessel below the level at which the abrading material is supplied thereto.

4. The method described, consisting in separating abrading material mixed with the liquid in a vessel into different grades, uil'lnlrzwving said grades in any desired sequence and conducting the same to grinding mechanism, returning the same to the grading vrssel and introducing the same into said vessel at a level intermediate the coarsest and finest grades withdrawn there- From, and eliminating the surplus liquid from various levels in said grading vessel While retaining therein the abrading material at aid levels. said grading. regrading. rm-ulation and elimination living married 0]) in an uninterrupted 'le with the material eon tanily mixed with the liquid.

5. The method desrrihed. runsisting in separating ahrading material mixed with. a liquid in a vessel into ditl'erent grades. hdrawing said grades in any desired sequence and rundurting the same to grinding meehanism. rewriting the same to the grading vessel and introduc'inr the same into said vew sel at a level internn'diate the eoarsrst and finest grades withdrawn. thrrefrnm. eliminating the surplus liquid from variona levels in said grading vessel while retaining therein the ahrading material at said levels. said grading. regrrading. t-irrulation and elimination living I'arried on in an uninterrupted ovrle with the material ronstantly mixed with the liquid. and siinultan-eousl) introdueing liquid into said vessel below the level from which the roarse material is withdrawn.

6. The method described. consisting: in separating ahrading material mixed with a liquid in a vessel into tilllblolllgrades. withdrawing the coarser grades separately and independently and eondurting the same to the grinding; merhanism during the rough grindiing operation. returning the same to the grading vessel and introducing the same into said vessel at a level internualiate the level of the coarsest and finest grades witlu drawn therefrom. said grading. rear-ailing and circulation being earl-led on in an uninterrupted eyrle with the material constantly mixed with the liquid rondensing the liner grades in said grading vessel. and withdrawing the same to the grinding apparatus lurin; the finishing operation.

7. The method desrrihml. ennaisting in separating ahrading material mixed with a liquid in a vessel into ditlereru grades. withdrawing said grades in any desired sequonre and eondurting the same to gg'rindiing int-rhanism. and returning the same to the grading vessel and intrmluring the same into said vessel at a level intermediate the roar est and finest grades withdrawn therel rmn.

R. The method desrrihed. eonsistiing in separating ahradina material mixed with a liquid in a vessel into ditlerent grades. withdrawing said grades in an desired sequence and rnmlnrtin; thr same to grinding ineehanism, returning the same to the grading vesso! and imrodnt-ing the same into said vessel at a level intermediate the coarsest. and finest grades withdrawn therefrom. and simultaneously introdneing liquid into said vessel below the level from which the course material is withdrawn.

l The method (ltstiihed. eonsisting in separating aim-ailing: material mixedwith a liquid in a Vessel tutu ditferent grades, Withdrawing said grades in any desired sequence and ondurting the same to grinding meehanism. and returning the same to the grradin vessel and intrmluring the same into said vessel at a. level intermediate the enarsest and finest grades withdrawn therefrom, said grading. regradina and circulation being; rarried on in an uninterrupted cycle with the material ronstlantly mixed with the liquid.

ll). The method described, consisting in separating ahrading material mixed with a. liquid in a vesse into different. grades. withdrawing said grades'in any desired seuuerne and eundueting the same to grinding mechanism, returning the. same to the grading ves.- sel and introducing the same into said vessel at a level intermediate the eoarsest; and finest grades withdrawn therefrom. and simultaneously intrndueing liquid into Said vessel helnw the level from which the coarse material is withdrawn, said grading, mgr-ailing and circulation luring rarried on man uninterrupted cycle with the material constantly mixed with the liquid.

11. The method deseril'ied. eonsistiing in separating: ahrading material mixed with a liquid in a vessel into difi'errnt grades. withdrawing said grades inde vendentlv from ditl'erent levels and eonduetmg the same to grinding mechanism. and returning the same to the ,afradiira vessel. and introducing the ame into titlltl vessel in a rising stream at a level intermediate the levels of the coarsest and finest. grades withdrawn there from.

12. The method described. consisting in separating alu-adiug material mixed with a. liquid in a vessel into ditl'erent grades, with drawin; said grades: indiwatndently from dillerent levels and r-ondurting the same tn grinding nu'ehanism. returning: the same to the grading: vessel and iatrodnring the same into said vessel in a ri ing stream at a level interlm-diate the levels of the real-seat and finest grades withdrawn then-tram. and simHItam'ously intrnduring liquid into said vessel lJtlUW the level from whirh th roarse material is withdraw-xii.

13. The method ilesurihed. ronasistina in suhjerting ahrading material mixed with a liquid to an upward flow or travel of the liquid relative to the material in a vessel and therelrv separating the. material into grades. introducing the material into the grading vessel at.- a level internnaliate the levels of the coarsest and finest grades withdrawn therefrom. simultaneously withdrawing coarse material from a level helm: the. level at \Vlllt'l] the material is inlrodueed into aid vessel and eondueting the same to the. grinding merhaniam. and returning the used material in susp nsion in :1 liquid to the grading vessel.

14. The method tlt'stlllled. consisting in subjecting abrasives to an upward flow or til) ,nism rclurnin'; the mud lillill'l'ill from ll'ui'i-l i i hr liquid rvluiiw in thc ulirsisivrs in u xc si-l, mid Harri-hr siizaruiiun' flu sumc inio grudrs. inirlidwriugg ihc rilu'usii'c into suid vr rl at u icvcl inirlilirdiuic lhc lci'cls oi ilw rozez'scsi and llIiiPl grudrs Withdrawn ihrrcl'rom. wiilsir ming rmlrsl- ;il)l'2\r-l\l' 'fl'ull! lllii i'i srl 1 point liulmv flux ntro dur'iion of ihc ilill'ilnlY into said csscl mid conducting: lhc umo in llll' grinding appumflis. and introducing liigi id into suid vcs- Hi l hclmv tho l(\'(l of tin: introduction of thc uhrusivc thrrrinto.

15. The nicthod dcscrihcd. consisting in subjecting :du-usivc to an upward low of trawl of the liquid rclnl'irc to thc lnzitci'inl in u vvsscl and lhrrvli scpuruling the sin-m sivc into gi'mh-s, iihdrzan n; this rc-zirsc mm tori-Lil from'thc linlllill: of Hlllll vcsscl and iondlu-iing tho rllllli is: i'liu grinding liifllld lhc grinding nioi'haznis to mid gr ding; vcssi-l and introducing liuniurncd sin-mire to the, grading \rsscl at u lcvcl iidcrmmliutc the h-vz-ls of thc cnul'srst and lincsi grndcs with drawn therefrom and rcgu uliiuz this circulalion from llw guiding vesscl in tho grinding nicrhuui m and rclurvr Iii. Tim nicihod dis-minimal on i ting; in whim-ting; iiiil'i$ l%( in in upward flow r imvcl ol' the liquid rclzzt'ii'u in ilw imiicriul in u \csscl and thud-la sriziruii iur; lhc uhrzc sivc iu'm grndrs, withdrawing ll ri'ml'su mu tclizil f om thc bottom of vi vr srl and muducting tho sumo in thc grinding lllt lllll" nisin, returning; tho nscd lilillllili from thc grinding mi-chnnism in said grading: Vit-Hil and llll!'(i(llll'lll,' i1l iriurucd zilmisivc 1o ihc .l'l'ililiilg \vssrl at It ic'wl iuici'imidiutc tho lcvcls of tho (Oi'LI'H'Hl and lincsl grmlcs )Yiilillrzmn ilu-rc'fruim ii'iiroducin; chm]- liquid into said vcsscl llllfii" ihc point of ilitrmlud tion of the :iin'usiw lvlilil'l'llllli and ridiculing the circulution from :Ihc grading: vessel to thc grinding gipurulus and rctiirn l7. Appm'uius of thc cluu'zirici' dcsrriliwi, cmi'iprising in combination, grinding: lillflll" nism, d, grading vessel. means for producing in said vessel an upward flow or travel of ihe liquid rchitive to thc inziicrisl to scpu rate thc mun-rial info grades msuns for con ducting diii'crcnt grudcs iiulcpcmlrufl from said vessel to the grinding mcchunisin, and mcuns for returning said imilm'iail in suspension in a liquid fr m ihc grinding mechanism to said vcsscl and introducing thc same lhcrciuto at u lcvcl infcrmmliutu lhc lcvcls of ihc coarscst and finest ,Qjrudvs witlulrmvn thcrciorm.

18. Apparatu of the character dcs frihcd, comprising in couihins iion, winding nicchzr nism, u Q'P'Klllll! Elilisil. prmlm-ing in said vr-s cl an upward lion .1 travail of thc liquid ri-liiiim in thc inn isi in sh n-1min lhc material into V For withdrawing different l3; and in uny desired sequence from said vessel and rolu'lurting the same to the grinding mechanism, and means for returning said material from the grinding mechanism and introducing the same into said vessel at a level iutcrmcdizite the levels it which the coarsest and finest grades are withdrawn therefrom.

l9. Apparatus of the character described, comprising in combination, grinding mechanism, a grading vessel, means for producing in said vessel an upward flow or travel of the liquid relative to the material to se aratc the material into grades, means or wiilu'lrziwing' different grades independently and in any desired sequence and conducting lhc smnc to the grinding mechanism, means for rcturning said material from the grinding mechanism and introducing the same into said vcsscl at a level intermediate the levels ill which thc coarsest and finest grade/sure withdrawn therefrom, and means for sup: plying liquid to said vessel at a level below the coarsest grade withdrawn therefrom.

20. Apparatus of the character described, comprising in combination, grinding mechanism. u grauling vessel, means for producing in s21 id Vessel, an upward flow or travel of the liquid relative to the material to separate the nuncriul into grades, means for conducting different grades independently from said vcsscl to the grinding mechanism, and moans for returning said material in suspension in a liquid from the grinding mechanism to said vessel and introducing the smile ihcrviuio in a rising stream of mixture at a lcvci intcrincdiafe the levels of the coarsest and fincst griuies withdrawn therefrom.

Apparatus of the character described,

comprising in combination, grinding mechanism, a grading vessel, means for producing in said vessel an upward flow or travel of lhc liquid rclativc to the material to sepamtc the material into grades, and means for rrturning said material in suspension in a. liquid from the grinding mechanism to said vessel and introducing the same thereinto in a rising stream of liquid at a. level intermelllillO thc levels of the coarsest and finest grades withdrawn therefrom.

22. Apparatus of the character described, comprising in combination, grinding mechanism, a grading vessel, means for producing in said vessel an upward flow or travel of the liquid relative to the material to separate the said material in suspension in a liquid from the grinding mechanism to said vessel and introducing the same thcreinto in a. rising stream of liquid at a level intermediate the icvcls of the coarsest and finest grades withdrawn therefrom, and means for introducing liquid into said vessel at a level below the level at which the coarsest material is withdrawn therefrom.

material into grades, means for returning i I 23. Apparatus of the character described, comprising in combination grinding meeha nism, a grading vessel, means for producing in said vessel an upward flow or travel (it the liquid relative to the material to separate the material into grades, means for returning said material in suspension in a, liquid from the grinding mechanism to said vessel and int-rodueing the same thereinto in a rising stream of'liquid at a level interme diate the levels of the coarsest and finest grades withdrawn therefrom, and means for eliminating surplus liquid from various levels in said vessel while retaining therein the various grades of ahrading materials at said levels.

21. l-kpparatus of the character described, comprising in combination, grinding mechanism. a grading vessel, means for producing in said vessel an upward flow or travel of the liquid relative to the material to separate the material into grades. means for returning said material in suspension in a liquid from the grinding mechanism to Said vessel and introdueing the same thereinto in a rising stream of liquid at a level intermediate the levels of the coarsest and finest grades withdrawn therefrom. means for in. trod ueing liquid into said vessel at a level he low the level at which the material is introduced thereto, and means for eliminating surplus liquid from various levels in said vessel while retaining therein the various grades of abrading materials at said levels.

Apparatus of the character described, comprising in combination, grinding mechanism, a grading vessel, means for producing in said vessel an upward flow or travel of the liquid relative to the material to separate the material intu grades, means for withdrawing different grades independently from Said vessel and conducting the same to the grinding meeaanisni, means for returning said material. from the grinding: mechanism and introducing the same into said vessel at a level intermediate the levels at which the coarsest and finest grades 'are withdrawn therefronn and a plurality of cones located at different levels in said vessel for withdrawing; superfluous liquid from said levels while retaining: and condensing the various grades in said vessel.

26. Apparatus of the eharaeter described, Comprising in combination, grinding mechanism, a grading vessel, means for producing in said vessel an upward flow or travel of the liquid relative to the material to separate the material into grades, means {or withdrawing different grades independently and eondurting the same to the grinding me ihanii-am, means for returning said material from th grinding mechanism and Introdueing the same into said vessel at a level intermediate the le els at \vhirh the eoarscst and finest grades are withdrawn therefrom. means for supplying liquid to said vessel at a level helrnv the coarsest grade:- withdrawn therefrom. and a plurality of cones at ditl'erent levels in said vessel for withdrawing superfluous liquid from said levels while retaining and condensing the various grades in said vessel,

Apparatus ot' the eharaeter desevilu-d, (annprisiug: in comhination, grinding marlin- IllSIlL a grading vessel mears for pr-uhu-uq; in said vessel an upward flmv isr travel of the liquid relative tmthe material in sepa rate the material into gradea means for returning said material in suspension in a liquid from the grinding meehanism to aaid vessel and introducing the same thereiuln in a riain r stream of liquid at a level irlew mediate the levels of the roarsesl and l'iuest grades Withdrawn therefronn and a plurality of cones loeated at dittercnt levels in said vessel for withdrawing Hlll'iil'llllflil'l li-z; aid from said levels While retaining and condensing the various grades in said vessel.

r'l]))]2\ltilllt-' of thc (liui'zuter deserihelh comprising in eondiinatinn grinding meeha nisna. a grading vessel. means 1'1 a" producing in said vessel an upward tlow or travel of the liquid relative to the material to separate the material into grades. means for returning said material in suspension in a liquid from the grinding mechanism to said vessel and introducing the same thcreinto in a. rising streani of liquid at a level inter mediate the level$ ol' the eoarsest and finest grades withdrawn therefroun means tor intrmlueing liquid into said vessel at a, level helo'w the level at which the material is introduced thereto, and a plurality of mixes lorated at dill'erent levels in said vessel for witlulrawingr superfluous liquid from said levels while retaining: and rondensing the var ous grades in said vessel.

in testimony whereof, I have hereunto set, my hand.

ALBERT K. lll'ltllttltlhL ll itnesses l lmuurr la llvnu. (ltnxs ll. lacanscun.

ill?) 

